Activation of the Wnt/β-Catenin Signaling Pathway by Mechanical Ventilation Is Associated with Ventilator-Induced Pulmonary Fibrosis in Healthy Lungs

Jesús Villar,Nuria E Cabrera,Francisco Valladares,María Elisa Quilez,Arthur S Slutsky,Carlos Flores,Norberto Santana-Rodríguez,Robert M Kacmarek,Milena Casula,Lluís Blanch,Cara Gottardi

doi:10.1371/journal.pone.0023914

Abstract

BackgroundMechanical ventilation (MV) with high tidal volumes (VT) can cause or aggravate lung damage, so-called ventilator induced lung injury (VILI). The relationship between specific mechanical events in the lung and the cellular responses that result in VILI remains incomplete. Since activation of Wnt/β-catenin signaling has been suggested to be central to mechanisms of lung healing and fibrosis, we hypothesized that the Wnt/β-catenin signaling plays a role during VILI.Methodology/Principal FindingsProspective, randomized, controlled animal study using adult, healthy, male Sprague-Dawley rats. Animals (n = 6/group) were randomized to spontaneous breathing or two strategies of MV for 4 hours: low tidal volume (VT) (6 mL/kg) or high VT (20 mL/kg). Histological evaluation of lung tissue, measurements of WNT5A, total β-catenin, non-phospho (Ser33/37/Thr41) β-catenin, matrix metalloproteinase-7 (MMP-7), cyclin D1, vascular endothelial growth factor (VEGF), and axis inhibition protein 2 (AXIN2) protein levels by Western blot, and WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, and AXIN2 immunohistochemical localization in the lungs were analyzed. High-VT MV caused lung inflammation and perivascular edema with cellular infiltrates and collagen deposition. Protein levels of WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, cyclin D1, VEGF, and AXIN2 in the lungs were increased in all ventilated animals although high-VT MV was associated with significantly higher levels of WNT5A, non-phospho (Ser33/37/Thr41) β-catenin, MMP-7, cyclin D1, VEGF, and AXIN2 levels.Conclusions/SignificanceOur findings demonstrate that the Wnt/β-catenin signaling pathway is modulated very early by MV in lungs without preexistent lung disease, suggesting that activation of this pathway could play an important role in both VILI and lung repair. Modulation of this pathway might represent a therapeutic option for prevention and/or management of VILI.

Highlights

Mechanical ventilation (MV) provides essential life support for critically ill patients, it can cause or aggravate lung damage, a phenomenon called ventilator-induced lung injury (VILI)
This signaling pathway has not been tested in the context of ventilator induced lung injury (VILI) in healthy animals. To test this hypothesis we examined the activation and localization of WNT5A, b-catenin and target gene products [matrix metalloproteinase-7 (MMP-7), cyclin D1, vascular endothelial growth factor (VEGF), and axis inhibition protein 2 (AXIN2)] in lungs of healthy animals ventilated with low and high VT
This study demonstrates that (i) WNT5A is expressed and localized in healthy lungs in response to MV in the absence of infection or toxics, (ii) the expression of WNT5A is dependent on the applied VT, (iii) activation of WNT5A and b-catenin are associated with up-regulation of downstream target genes, and (iv) pulmonary fibrosis is induced very early during VILI

Summary

Introduction

Mechanical ventilation (MV) provides essential life support for critically ill patients, it can cause or aggravate lung damage, a phenomenon called ventilator-induced lung injury (VILI). Insights into the physiology of VILI come from animal studies demonstrating that MV with larger tidal volumes (VT) rapidly resulted in pulmonary changes that mimic acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) [1]. Doi:10.1371/journal.pone.0023914.t001 p-value surfactant, stress response, cytoskeletal structure, oxidative injury, and endothelial/epithelial barrier dysfunction [4,6,7,8]. Despite these advances, understanding of the relationship between specific mechanical events in the lung and the cellular responses that result in VILI remains incomplete. Mechanical ventilation (MV) with high tidal volumes (VT) can cause or aggravate lung damage, so-called ventilator induced lung injury (VILI). Since activation of Wnt/b-catenin signaling has been suggested to be central to mechanisms of lung healing and fibrosis, we hypothesized that the Wnt/b-catenin signaling plays a role during VILI

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